Perhaps on of the most ingrained and contentious habits of bookbinders and conservators is if the leave the blade of the board shear up or down. Once you are in the habit of leaving it one way of the other, it is virtually impossible to change. So if you use a board shear please take a second to fill out the poll below and the results will be immediately calculated. I realize this is perhaps not the most important topic I could be thinking about, but the new poll option was introduced this week on wordpress, so I guess this is a good example of how technology drives and influences content.
THE ARGUMENT FOR LEAVING THE BLADE UP
I confess I fall into this camp. I find it much faster, when approaching the board shear to be able to immediately able place the material to be cut under the fence, and slide it into place without having to lift the blade first. Also, when the blade is up, it sticks out less, so there is less of a chance of running into the handle or counterweight, which is a more common injury than cutting yourself on the blade.
THE ARGUMENT FOR LEAVING THE BLADE DOWN
It is dangerous to leave the blade up for two reasons. First, although the blade has a fairly obtuse angle, it is still possible to cut yourself on it, and it just looks dangerous, this long blade sticking up in the air. Second it is more likely that the counterweight could slide off the end (especially if you haven’t drilled through the bar and inserted a bolt) and the weight of the blade would come crashing down on whatever happens to be under it.
Peachey Conservation 
For whatever it is worth, I’ve cut my hand on a blade someone left up, so whenever I see the blade up, I put it down. So the problem of cutting your hand is possibly not as rare as you think….
If you cut to the line instead of cutting with the gauges, you must have your head over the lower blade’s edge and near to it. In this case it is clearly much safer to have the blade up than down. Also, if you leave the blade down you are apt to walk into the handle. Not comfortable.
Far more important, however, than the simple matter of blade up or down is having the blade balanced either for up or down, and to keep it in the safe position. A blade balanced for “neutral” is a major danger because it can be easily knocked either way. And the blade must never be left in any position except the safe position as it is currently balanced— so, **never** anywhere except fully up or down. Furthermore, never meddle with the blade position in a bindery where you don’t know what position the blade is balanced for. To do so is ill-mannered as well as unsafe.
While working I leave it up..Otherwise for safety I keep it down.